I spoke to HR when I went for my psychometric test and was told that it will take them 1-2 weeks to contact you if you are rejected and 3-4 weeks if you are further shortlisted. So far, I have taken the test, written 2 short essays and went for an interview. I was told if I was further shortlisted I will have to go for another interview before clearance. Considering the wide variety of positions MINDEF looks for, the procedures can be very different, I am guessing that the middle stages can be different for each position; psychometric test and clearance are probably the only stages all applicants will have to go through.